[Bounty] Add isValidAccountId function

[willemneal]

When dealing with account identifiers (accountId's) in smart contracts it is important that they can be validated.

API

//   This method is a simple string validation of accountId's.
function isValidAccountID(accountId: string): boolean

Implementation

Place the function in the env namespace.

Here is the rust implementation for guide.

Testing

Add tests here.

[gitcoinbot]

Issue Status: 1. Open 2. Started 3. Submitted 4. Done

---

Work has been started.

These users each claimed they can complete the work by 266 years, 3 months from now.
Please review their action plans below:

1) luciotato has been approved to start work.

I plan to translate rust to ts and then write 4 test assertions
2) nightwolf3 has applied to start work (Funders only: approve worker | reject worker).

I think I'm up for the task, already have experience in TS but reading the Rust implementation might take some time
3) vbstreetz has applied to start work (Funders only: approve worker | reject worker).

Had a go at https://bit.ly/2BYohDN and, was expecting https://bit.ly/2BYohDN to work but getting https://imgur.com/a/aLg2DXx error. Isn't near-sdk-as just a binding to near-sdk-rs?

Learn more on the Gitcoin Issue Details page.

[luciotato]

I've added the function as requested
#203